1. Field of the Invention
The present invention relates to implantable medical tissue stimulating devices and, more particularly, to implantable leads for connection to such medical devices.
2. Background of the Related Art
Implantable leads are used in conjunction with a variety of medical devices to transmit electrical signals to the devices from a target location in the body and/or stimuli from the devices to the target location. The implantable leads are typically manufactured as separate components of a tissue stimulating system rather than being a part of the tissue stimulator itself. Therefore, the lead typically requires an interconnection to the implantable medical device with which it is used. This interconnection includes a connector assembly that is located on the proximal end of an elongated lead body. The connector is adapted to be inserted into a header port in the medical tissue stimulating device.
Currently, electrical connector assemblies on leads used to connect to cardiac pacemakers generally correspond to the IS-1 connector standard. Alternatively, connector assemblies used to connect to implantable defibrillators and, particularly, those used in conjunction with high energy cardioversion and defibrillation electrodes may correspond to the DF-1 connector standard.
In addition to conforming to the various standards, the connector assemblies typically include one or more sealing rings to seal the header ports. The seals are configured to prevent fluid entry into the medical device and to form seal between the individual electrical contacts on the connector assembly when the connector assembly is seated in the header port. The seals are typically tightly squeezed between the connector assembly and the header port to form the seal. The compression of the seals increases the force required to insert the connector assembly into the header port. In addition, the frictional resistance further increases the force necessary for insertion. In use, the force necessary for insertion is applied to the proximal end of the lead body adjacent to the connector assembly. Due to the flexibility of the lead body, it has a tendency to buckle or kink during insertion of the connector into its socket of the device""s header. The buckling or kinking can damage the lead""s conductors that may result in the lead failing and thus, having to be abandoned or explanted. Alternatively, the lead body may be bent so that force may be applied to the relatively rigid connector assembly""s distal end. Again, the bending of the conductors and application of a compressing force has a tendency to kink and break the conductors and/or insulation within the lead body resulting in the need to replace the whole lead. Therefore, a need exists for a connector assembly that permits the application of requisite force for seating the lead connector without the buckling or kinking of the lead""s conductors.
Current leads typically employ one of two general mechanisms to assist inserting the lead""s connector assembly into the header port of the medical device. The first mechanism consists of a coil or tube, mounted within the lead body and which extends distally from the proximal end of the lead body. This coil or tube provides the proximal end of the lead body with increased column strength and rigidity to assist insertion of the connector assembly into the header port. The coil or tube provides rigidity to the adjacent lead body but the coil or tube does not provide a gripping surface nor does the coil or tube address the innate tendency for a medical professional to push on the end of the coil or tube by bending the lead body at the distal end of the coil or tube and pushing with the thumb, an approach which tends to damage the conductors. The second mechanism consists of a stress relief sleeve mounted over a proximal portion of the lead body. The stress relief sleeve provides a grip which the physician may grasp when inserting the lead. Although the stress relief sleeve may reduce the amount of buckling or kinking, the sleeve only provides structure for gripping the lead body between two fingers and again does not address the innate tendency of a user to want to push with his/her thumb. Therefore, a need exists for a design for the proximal end of a lead that allows for users to push the connector assembly into the header port with his/her thumbs without increasing the risk of damaging the conductors.
The present invention provides a medical lead providing an angled collar configured to aid the user in the insertion of the connector region into the header port without damaging the lead by providing a surface on which to press and thereby apply a force along the longitudinal axis of the connector. The medical lead, in accordance with the invention, comprises an insulating lead body having a proximal end and a distal end and at least one conductor extending therebetween, and having a male connector member attached to the conductor of the lead body at the proximal end thereof. An angled collar is attached to the lead body adjacent the connector assembly. The angled collar is configured to provide a surface that when pressed, causes a force to be applied along a longitudinal axis of the connector assembly to facilitate insertion of the connector assembly into a female header port.